What does mitochondrion do for the cell?
it is the powerhouse of cell .it supplies the energy to the cell .
Not exactly. Energy is neither created nor destroyed, it only changes form (this is Physics (the first law of thermodynamics, to be precise)). The mitochondrion is important to the cell because it is here that most of the energy is released from food into a form the cell can use. You can think of a mitochondrion as like a power station for the cell.